Digital video compression methods work by exploiting data redundancy in a video sequence (i.e., a sequence of digitized pictures). There are two types of redundancies exploited in a video sequence, namely, spatial and temporal, as is the case in existing video coding standards. A description of one of these standards can be found in the following publication, which is hereby incorporated herein by reference: ISO/IEC International Standard IS 11172-2, “Information technology—Coding of moving pictures and associated audio for digital storage media at up to about 1.5 Mbits/s—Part 2: video,” 1993.
Compressed video streams typically include independent and dependent pictures. An independent picture is coded using information only from itself whereas a dependent picture is coded using information from one or more other pictures. An example of an independent picture is an Intracoded picture, often referred to as an I-frame. I-frames are typically compressed by exploiting the internal spatial redundancy of rectangular (or square) regions independently of reference pictures, or by predicting the information within a rectangular region from the decompressed representation of other rectangular regions in the picture that have undergone compression. The first picture of a compressed video sequence is typically, but not necessarily, an I-frame. Examples of dependent frames are predictive pictures (also known as P-frames), and bi-directional pictures (also known as B-frames). P-frames are pictures in which each of its rectangular regions can be compressed by predicting their value from the decompressed representation of any one of possibly several reference pictures. A past reference picture is a picture that is to be displayed prior to the current picture. B-frames are pictures in which rectangular regions can be compressed by predicting their value from any two reference pictures such as a past reference picture and a future reference picture. A future reference picture is a picture that is to be displayed after the current picture.
A compressed sequence of pictures results in a video bitstream, also called a compressed video stream, that can be decompressed to provide any playback mode, including trick modes such as fast-forward playback and reverse playback viewing of a television program or movie. Often during trick modes, pictures are displayed multiple times consecutively to effect the instantiation of the trick mode. However, a television picture scan format at its time of creation coupled with compression schemes that encode pictures or parts thereof in one or more different scan formats exhibit compounded artifacts when the pictures are displayed. For example, a slow forward or slow reverse operation may require a picture to be displayed repeatedly over multiple consecutive “picture display” intervals. In the case of interlaced video captured by a camera at every field interval, such as 1/60th of a second apart, if both fields of the picture are displayed repeatedly in their intended order over multiple consecutive picture display intervals in an interlaced display, motion jitter may be exhibited during the displayed instance of the video in the slow forward or slow reverse operation. This is exacerbated in high motion video sequences. The problem is also manifested in some fast playback operations. Similarly, displaying the same two fields in a progressive display repeatedly over multiple consecutive picture display intervals may exhibit discontinuities in the contours of objects as a result of the displacement caused by the motion. Some decoding and/or display methods address these problems by providing only one field of the picture twice or scaling the field by two in the vertical orientation, often at the expense of picture quality. Therefore, there exists a need for systems and methods that address at least some of the aforementioned and/or other deficiencies and/or inadequacies.